Saturated aliphatic dicarboxylic acid salts as detergent builders

ABSTRACT

DISCLOSED HEREIN ARE DETERGENT COMPOSITIONS WHICH INCLUDE A DETERGENT COMPOUND AND AT LEAST ONE BUILDER SALT. THE MAJOR PORTION OF THE BUILDER SALT IS AN ALKALI METAL SALT, AN AMMONIUM SALT OR MIXTURES THEREOF OF AN ALIPHATIC SATURATED POLYCARBOXYLIC ACID HAVING A LINEAR CARBON CHAIN OF FROM TWO TO TEN CARBON ATOMS, SALTS OF OXALIC AND SUCCINIC ACID ARE PREFERRED. NO POLYPHOSPHATES ARE REQUIRED.

United States Patent Office 3,661,787 Patented May 9, 1972 3 661 787 SATURATED ALIPHATIC DICARBOXYLIC ACID SALTS AS DETERGENT BUILDERS George E. Brown, Jr., Cincinnati, Ohio, assignor to The Pollutrol Group, Cincinnati, Ohio No Drawing. Filed Oct. 9, 1970, Ser. No. 79,691 Int. Cl. C02b 5/06; C07c 55/02; Clld 9/26 U.S. Cl. 252-109 2 Claims ABSTRACT OF THE DISCLOSURE CROSS REFERENCE TO RELATED APPLICATION Filed on even date herewith are two other applications of the inventor, George 'E. Brown, Jr., entitled Detergent Compositions which disclose other detergent compositions which include a polyphosphate substitute.

BACKGROUND OF THE INVENTION AND THE PRIOR ART In signing the National Environmental Policy Act on I an. 1, 1970 President Nixon declared that America must reclaim the purity of its air and water. In furtherance of our governments objectives of eliminating pollution a Presidential Commission was appointed to study the causes of pollution and to recommend solutions thereto. On Aug. 10, 1970 their initial report was made public. It included as one recommendation for reclaiming our waters that polyphosphate builders be eliminated from detergent compositions.

For a number of years now, the polyphosphates and especially sodium tripolyphosphate ('STP) and tetrasodium pyrophosphate (TSPP) have been the backbone of detergent compositions. The role of these builders is a complex one but two of their principal, required functions are to sequester calcium and magnesium salts in the wash water and to enhance the cleaning capabilities of detergent compounds.

Millions of tons of the polyphosphates are sold annually in the United States for use as builders. Sometime during the life span of these detergents they are usually discharged into our nations lakes and streams.

In recent years a growing amount of evidence has indicated that the polyphosphates have deleterious effects on our streams and lakes. For example, it has been observed that the growth of certain algae in bodies of water is stimulated by the polyphosphates, thus causing serious damage to various kinds of aquatic plants and fish. The algae buildup also produces a very unpleasant sight. And, before too long, conventional water sports are no longer possible.

Prior to the Environmental Act of :1970, one of the largest concerted industrial efforts Was instituted to discover a satisfactory, nonpolluting replacement for the polyphosphates in detergent compositions. It is still being actively pursued. Recently, one major seller of cleaning products advertised that it had, without success, spent over three million dollars in an effort to discover such a replacement. Despite this concerted effort, no such replacement has been announced by anyone.

Other builder detergent salts are known or have been announced. Some supposedly present no pollution problems. While they are thus superior to the polyphosphates in that respect they are inferior in other ways. For example, some have been too costly to manufacture, others have failed to function properly as builders, to display the required synergistic action in combination with detergent compounds, and still others have become suspect of producing undesirable side effects.

One builder salt which some detergent manufacturers have recently begun commercially using is the trisodium salt of nitrilotriacetic acid. While the use of this salt has reduced the amounts of polyphosphates required in a particular detergent composition, it has not eliminated the polyphosphates entirely. In such compositions polyphosphates are still employed. Moreover, in recent months some opinions have been expressed that this compound may contribute to the growth of, or cause cancer.

Builder salts other than the alkali metal salts of the aminopolycarboxylic acids have been proposed as polyphosphate replacements. For instance, in Diehl U.S. Pat. No. 3,308,067, a polyphosphate substitute is disclosed. The inventor describes his builder salts as being water soluble salts of polymeric aliphatic polycarboxylic acids. He describes the essential structural characteristics of such salts as follows:

(1) A minimum molecular weight of about 350 calculated as the acid form.

(2) An equivalent weight of about 50 to about calculated as the acid form.

(3) At least 45 mole percent of the monomeric species comprising the polymer aliphatic polycarboxylic acid species havingat least two carboxyl radicals separated from each other by not more than two carbon atoms.

(4) And, the site of attachment to the polymer chain of any carboxyl-containing radical being separated by not more than three carbon atoms along the polymer chain from the site of attachment of the next carboxyl-con- .taining radical.

He points out later in the patent that as the molecular Weight decreases below 350, the builder properties decrease substantially.

Still other builder salts have been produced as polyphosphate replacements namely, sodium phytate, the water soluble salts of methylene diphosphoric acid, etc. A review of such salts and the patents disclosing them is contained in U.S. Pat. 3,346,873.

Despite the millions of dollars which have been spent in an attempt to discover polyphosphate replacements there has been no compound discovered which favorably compares with the polyphosphates on a price and performance basis and which eliminates the pollution problem. To these ends this invention is directed.

SUMMARY OF THE INVENTION It has been quite unexpectedly discovered that the alkali metal salts and/ or the ammonium salts, of the aliphatic saturated carboxylic acids, dibasic or polybasic, having linear carbon chain lengths of two to ten carbon atoms, can be used as complete replacements for the polyphosphates. Such salts modified by a condensation reaction with urea or ammonia may also be used. No other builder salts are required. Such builder salts compare favorably with the polyphosphates and also eliminate the pollution problem.

It is known that the sodium salts of the dibasic saturated carboxylic acids have been used before in connection with soap (U.S. Pat. No. 2,792,348) and in detergent compositions (US. Pat. No. 2,878,190). In both patents the salts are employed in minor amounts. In the 348 patent they are used in an amount of from 1 to by weight and their presence is for the purpose of hardening the soaps they are used in connection with. The patent does not disclose or suggest that such salts may be used as builders nor that substantial quantities should be used. In the 190 patent minor amounts of water soluble salts of snccinic acid are disclosed for use in detergent compositions to reduce skin irritation. There is no suggestion that said salts can be used as builders and in fact the patent teaches that such additives are to be used in minor amounts and that major amounts of the conventional polyphosphate builders are required.

DESCRIPTION OF THE PREFERRED EMBODIMENTS It has been found that the polyphosphates and/or the other heretofore employed builder salts can be replaced in their entirety by the builder salts produced in accordance with the following description.

It has been discovered that suitable builder salts may be formulated from the saturated linear aliphatic polycarboxylic acids having a carbon chain length of from two to ten carbon atoms. The dibasic saturated acids, namely oxalic, malonic, succinic, glutaric, adipic, pimilic, suberic, azelaic, and sebacic, are included in this definition. The sodium salts of these acids are the preferred builder salts of this invention but the other alkali metal salts and the ammonium salts may also be employed. In addition to the dibasic saturated aliphatic acids other linear saturated polybasic aliphatic acids having carbon chain lengths of from two to ten carbon atoms may be employed. Citric acid is an example of such an acid.

It has been found that it is preferable to use the double salt of the foregoing dibasic acids rather than the mono salt. In the case of citric acid it is preferable to use the tri salt. Those skilled in the art will recognize that these salts may be formed in any of a number of ways and their specific method of formation forms no basis of my invention.

If desired, a monosodium salt of a dibasic saturated acid may be condensed with urea or ammonia. This may be desirable in the case of the salt of oxalic acid in order to eliminate any toxicity problem which otherwise might be present with the disodium salt. In preparing such a salt two moles of monosodium oxalate are condensed with one mole of urea.

In formulating a detergent composition it should include at least, on a weight basis, about 10% by weight of these builder salts. The amount required in a particular detergent composition is approximately equal to the amount of polyphosphates which would be suitable for use in that composition.

While other conventional builder salts may be used with these builder salts, such as the salts of nitrilotriacetic acid, sodium tripolyphosphate and tetrasodium pyrophosphate, their addition is not required. If such are included then they should be used in minor amounts--the builder salts of the present invention should be principally re sponsible for performing the builder salt functions. They should, therefore, constitute the major portion of the builder salts employed.

In the mechanical washing of clothes and other articles of cloth and like materials customarily washed in mechanical washing machines, it has been found that excellent results may be obtained if my detergent compositions are employed in amounts so as to provide in an aqueous solution a concentration about equal to that which would be obtained if conventional compositions were employed.

In formulating detergent compositions conventional detergents may be use in conjunction with my builder salts. Anionic detergents as well as the nonionic detergents may be. employed. Likewise, conventional soaps may be used with my builder salts and the term detergents should be understood to include soaps also.

In formulating detergent compositions with my builder salts it may be desirable to add materials which are conventionally added to detergent compositions, as for example pH and corrosion inhibitors such as sodium silicate, and anti-foaming agents, dyes, fluorescent compounds, etc.

If desired, these detergent compositions may be made up in liquid form. This may be done by customary techniques as for example by using water or alcohol or mixtures of the two along with solubilizing agents.

The preferred builder salts of this invention are disodium oxalate and disodium succinate. These builder salts are shown in actual tests, described in more detail hereinafter, to be as elfective as sodium tripolyphosphate when used as builders in detergent compositions. The following examples serve to illustrate these and other builder salts forming a part of this invention, the amounts to be used, and the detergent compositions which may be formed therefrom.

EXAMPLE 1 An excellent detergent composition givingoutstanding results in cloth washing has the following composition in the percentages (by weight) indicated.

A detergent, for example Orvus AB-a detergent of the linear sodium alkyl benzene sulfonate type 45 Disodium oxalate 45 Sodium silicate (Na O:SiO =1:1) -e l0 EXAMPLE 2 An excellent detergent composition may be formulated from the following materials in the percentages (by weight) indicated.

A soap consisting basically of potassium palmitate 40 Disodium oxalate 50 Sodium silicate (Na O:SiO =1:1) l0 EXAMPLE 3 The same amount of disodium succinate may be substi tnted for the disodium oxalate in Example 1 or 2. The remainder of the ingredients and their quantities may remain, the same. Cleaning results using this composition will not be quite so good as those obtained from using the compositions of Example 1 or 2.

EXAMPLE 4 The same amount of disodium adipate may be substituted for the disodium oxalate in Example 1 or 2. The remainder of ,the ingredients and their quantities may remain the same. Cleaning results using these compositions will not be quite so good as those obtained from using the compositions of Example 1 or 2.

EXAMPLE 5 The same amount of disodium azelate may be substituted for the disodium oxalate in Example 1 or 2. The remainder of the ingredients and their quantities may be the same. Cleaning results using this composition will not be quite so good as those obtained from using the composition of Example 1 or 2.

EXAMPLE 6 EXAMPLE 7 Excellent detergent compositions may be made by using a mixture of builder salts of this invention. For instance,

a detergent composition may be formulated from the following ingredients expressed in percentages on a Weight basis.

A detergent, for example Orvus AB-a detergent of the linear sodium alkyl benzene sulfonate type 40 Disodium oxalate 30 Disodium succinate 30 EXAMPLE 8 The salt of the polycarboxylic acid need not be the sodium salt as illustrated in the foregoing examples. It may be the salt of the other alkali materials or of ammonium. For instance, a detergent composition may be formulated from the following ingredients expressed in percentages by weight.

A detergent, for example Orvus AB-a detergent of the linear sodium alkyl benzene sulfonate type 40 Diammonium oxalate 30 Disodium succinate 30 EXAMPLE 9 An excellent detergent composition may be formulated with a detergent and a builder salt which consists of the condensation product of the reaction of two moles of monosodium oxalate and one mole of urea or ammonia. Such a detergent composition may be formulated from the following ingredients expressed in percentages on a weight basis.

A detergent, for example Orvus AB-a detergent of the linear sodium alkyl benzene sulfonate type 45 The condensation product of two moles of sodium oxalate and one mole of urea 45 Sodium silicate (Na O:SiO =l:1) 10 In order to test the effectiveness of the foregoing detergent compositions the following tests were made comparing them to conventional detergent compositions.

Towels having been treated with a standard dirt composition were used for test pieces. The washing cycles used for test purposes, the concentrations used, etc., were closely controlled so that the difference in cleanliness, etc., could only be attributable to the detergent composition utilized.

The standard dirt compound was made from one gallon of water, 20 grams of carbon black (of 324 mesh or better), 250 grams of soil, and 50 grams of castor oil. This standard dirt compound was made by mixing the latter three materials with a small amount of water in a Waring Blendor for five minutes and then mixing the resultant mixture with the remainder of the water.

The white towels used as test samples were previously washed to remove the sizing and fabric conditioners. The test towels were dipped immediately into the standard dirt compound after it was prepared. The towels were then dried before they were washed with the various detergent compositions.

In test 1 a test towel, designated 'ITl, was washed in a conventional detergent composition consisting of 45% by weight of a detergent, 45% by weight of a builder salt and 10% by weight sodium silicate (1 to 1 ratio). The builder salt was sodium tripolyphosphate, and the detergent was Orvus AB, a linear sodium alkyl benzesulfonate. The towel washed with this detergent composition was used as one standard for comparing the effectiveness of the detergent compositions produced in accordance with the invention disclosed herein.

Another standard towel, TT2, was washed with another conventional detergent composition consisting essentially of 40% by weight Orvus AB, 30% by weight STP, 20% by weight NTA and 10% by weight of sodium silicate.

A test towel, TT3, was washed with a detergent composition formulated in accordance with Example 1 hereof. ITS was compared with '[TI and was found to be as white as the standard towel. The amount of soil removed from TT3 was about equal to the amount of soil removed from TTl. The two towels appeared to have been washed with the same detergent composition.

A detergent composition formulated in accordance with Example 3 was used to wash another test towel, TT4. As before, soil removal, whiteness maintenance and general cleaning power appeared to be about equal between TT4 and TF1. The general appearance of the two towels appeared to be the same.

In another test a detergent composition having a formulation similar to Example 4 was used to wash a test towel, TT5. The results when TT5 was compared with 'ITl were not quite as good as the ones obtained by using Example 1 or 3 but still it was obvious that the builder salt did enhance the cleaning action of the detergent and perform the other essential functions of a builder salt.

In addition to the various materials which may be added to my detergent compositions as enumerated above, I have found that my builder salts seem to function extremely well with minor amounts of trisodium nitrilotriacetate.

EXAMPLE 10 It has been found that an excellent detergent composition may be formulated from about 30% by weight of one of my builder salts, preferably disodium oxalate, 40% by weight of Orvus AB or the equivalent, about 20% by weight of NTA and about 10% by weight of sodium silicate. A test towel washed with such a composition, TT6, was compared with a test towel, TT7, washed with an identical composition except that STP was used in place of the disodium oxalate. Soil removal, whiteness and general cleaning power were equal for the two compositions.

EXAMPLE 11 A detergent composition may be formulated from the following materials in the percentages (by weight) indicated.

' Percent A detergent, for example Igepal CO610a detergent of the monyl phenoxy polyethyleneoxyethanol (61% ethylene oxide) type 25 Disodium oxalate 75 References Cited UNITED STATES PATENTS 3,580,852 5/1971 Yang 252135 3,425,948 2/1969 Otrhalek 252-135 X 3,368,978 2/ 1968 Irani 252-527 X 3,308,067 3/ 1967 Diehl 252558 3,214,380 10/ 1965 Gangwisch 252 2,982,739 5/ 1961 Dvorkovitz et a1. 252156 2,264,103 11/1941 Tucker 252-132 X LEON D. ROSDOL, Primary Examiner D. L. ALBRECHT, Assistant Examiner US. Cl. X.R.

252-89, 108, 110, 132, 135, 156, 160, 180, 539, 558, DIG 1l;260-537, 538 

